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Old 06-27-2013, 11:27 AM
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Join Date: Dec 2012
Posts: 36
1974 280C Ignition Switch Issue

I just started to have problems with my 1974 280C this week. I'm suspecting the ignition switch, but I wanted to get some other opinions before I tie into that project.

The motor will not shutoff when I turn the ignition switch to off. All of the electrical equipment (radio, etc.) shuts off but the engine stays running. If I put the car in gear it shuts off. I'm assuming the neutral switch is actually what is turning the engine off when I put it in gear.

Any thoughts?

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Old 06-27-2013, 05:54 PM
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Join Date: Jan 2006
Location: Tucson, AZ
Posts: 4,719
Not the neutral safety. That only works within the "start" circuit.
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now
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Old 06-27-2013, 08:12 PM
Join Date: Sep 2005
Posts: 664
It sounds like the switch is just worn. I have seen these wear by the thickness of a sheet of paper and that would cause them to malfunction.

The worst part of all was tracking the problem. The switch worked fine on the bench but not at all on the car. It was all a matter of less than one mm.

You might look for a good used switch or try to find one new, but I think this is the only solution short of pulling your current switch apart and trying to clean out the insides of dirt and brass shavings.

And there is also the matter of it just being out of adjustment. Perhaps the key is not turning the lock cylinder far enough to place the switch in the kill position?
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Old 07-01-2013, 10:47 AM
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Join Date: Dec 2012
Posts: 36
A Little Air goes a long way

After reading some of the responses concerning debris and/or brass filings in the ignition switch, I decided to try something simple. I took my air nozzle and blew into the key slot. I thought I felt something hit me in the face, but anyway I started the car back off, turned the ignition switch to off and everything (including the engine) shut off. So for now the problem is fixed (kind of).
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Old 07-01-2013, 11:24 AM
Join Date: Sep 2005
Posts: 664
The inside of the ignition lock, which is different from the ignition switch, is full of pins and springs and all of them are tiny.

If one of them wore to the point it was hanging up it could keep your key from turning the lever on the end of the lock, the one that goes into the switch, far enough.

It sounds like you got it with the air blast. I have taken them apart and just tossed out the pin and/or spring that was worn. As long as you have one pin working it will keep the lock from turning without a key.

You can also remove all the pins and springs and just not tell anyone. Then your key will turn the lock as good as any screwdriver blade, but as long as you are the only one that knows this.......

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